Back in the 1940s, the U.S. Forest Service began a public service campaign aimed at preventing forest fires. It featured Smokey Bear, a humanized caricature of a bear wearing blue jeans and a ranger’s hat. In a kind, gravelly voice, Smokey enlisted public support with slogans, his most famous being: “Remember — only you can prevent forest fires.” Smokey’s effort is considered one of the most enduring and effective advertising campaigns of all time.

I know the ads worked for me as a boy. I grew up in a heavily wooded area, and became extremely cautious about matches and campfires as a result of Smokey’s message, as did all my friends. But why were we all so responsive to these ads? Was it the message of civic responsibility and public good? Fear of burning? Growing environmental awareness? Or was it Smokey himself, with his kind voice and sad eyes?

A new study gives Smokey the credit — specifically his voice, his face, the jeans and hat and shovel — the humanized Smokey. According to psychological scientist Hee-Kyung Ahn of Hanyang University, Korea, it’s this humanizing of a cause that makes people responsiv